Housing, with a tubular connector, for a heart stimulator

ABSTRACT

The present invention relates to a pacer housing ( 60 ) comprising a connecter means adapted to receive a connect plug ( 110 ) on the proximal end of a lead ( 15 ) with an electrode located on the dismal end of said lead, said housing being made of metal, and connecter means comprising a tubular member having two ends and being located inside said housing, a first end ( 22, 122 ) of said tubular member being welded or bonded to an opening in a wall of said housing, the second end ( 23, 123 ) of said tubular member being closed. Said tubular member comprises a tube ( 21, 121 ) made of a metal being weldable or bondable to said metal housing, said tube being structurally intact along its entire length, all interior means ( 27, 127, 28, 128, 50, 150, 51, 151 ) in said tube for contacting the contact surfaces ( 111, 118 ) on said plug being located within the enclosure formed by said tube, said tube further containing at least one insulating ceramic plug ( 26, 126 ) being coaxial with said tube and holding said interior means for contacting said contact surfaces on said plug.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to pacer housings and more particularly tothose parts of the housing intended for connection to the electrodeleads.

2. Description of the Prior Art

Implantable pacers normally have a pacer housing (also called can)containing electronic circuitry and a unit for electric power as well asdifferent electrodes which are connected to the interior parts in thepacer housing and which are to be implanted in or in the vicinity of theheart. The electrodes are connected to the pacer by means of leads. Theinternal parts of the pacers have to be well protected against theinternal environment, especially the body fluids in the body for a longperiod of time, which places strict requirements on all entries into theinterior of the can and especially on the connections of the leads tothe housing. At the same time it should be possible to disconnect thepacer from the implanted leads for replacement or servicing of thepacer. The connective parts of the pacer and the leads have largely beenstandardized so as to encompass a relatively deep female socketcomprising a number of contact surfaces whereas the leads are providedwith a male part comprising one or several corresponding peripheral,generally circular contact surfaces.

At present the connective part of the pacer housing containing thefemale socket is made of a transparent material, normally epoxy resin,which is molded onto the housing and onto contacts extending outwardlyfrom the housing. The male part of the leads is normally locked by meansof set-screws, although other fastening means have been envisaged. Thepositioning and alignment of the different contact surfaces and of thefastening means or metallic threads for the set screws prior to themolding of the connective part is however very complicated and the delayin the manufacturing process incurred by the curing of the epoxy resinis considerable.

It would thus be desirable if the molding procedure could be dispensedwith.

It has been discussed that these complexities could be avoided bydesigning the pacer with a socket located inside the metal housing. Thiskind of socket, sometimes termed “black holes”, is not used at present.

U.S. Pat. Nos 4,934,366 and 5,324,111, the teachings of both of whichare incorporated herein by reference, describe two interior sockets orblack holes for pacers. Both designs have a tubular member formed by anumber of alternating sections made of metal and insulating ceramic,respectively. An end section of metal can be welded or bonded to anopening in the pacer housing by means of a flange. The use of differentmaterials, however, sets high standards in regard of precision anddurability of the component parts and as well as on the assemblyprocedure thereof. This is especially important since the interiorsockets must meet very high standards regarding the integrity of theinterior of the pacer housing during long times of implantation in ademanding environment. The manufacture of these known sockets thus isrelatively complicated. The same is true for the device disclosed inU.S. Pat. No. 4,262,982, a ceramic socket combined with a metal flangefor welding to a pacer housing and with a metallic interior contact pin.This device also has locking means in the form of an inwardly directed,circumferential rib located adjacent the opening of socket. This rib isintended to cooperate with barb-shaped sealing rings on the contact plugon the proximal end of the lead or catheter.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a pacer housing which allowsthe molding procedure to be avoided and the design of an interior socketto be simplified to a high degree while still meeting the required highstandards

The above object is achieved in accordance with the principles of thepresent invention in a pacemaker housing having a connector arrangementwhich is adapted to receive a contact plug at the proximal end of alead, the pacemaker housing having a housing enclosure made of metal andthe connector arrangement forming a tubular member with two oppositeends disposed inside of the housing. A first end of the tubular memberis open and is welded or bonded to an opening in the wall of thehousing. The second end of the tubular member is closed. The tubularmember is made of metal that is weldable or bondable to the metalhousing. The tubular member is structurally intact along its entirelength. A number of interior components, adapted for mechanical andelectrical contact with contact surfaces of the contact plug of thelead, are held in an insulating ceramic plug which is located in theinterior of the tubular member and is coaxial therewith.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a conventional pacer housing having atransparent molded connector part.

FIG. 2 shows a lead with a male connector plug, of the type used withthe inventive pacer housing.

FIG. 3 shows an exploded view of various components of a connective partconstructed in accordance with the principles of the present invention.

FIG. 4 is a side sectional view of an assembled connective partconstructed in accordance with the principles of the present invention.

FIG. 5 is a side sectional view of a portion of a pacer housingconstructed in accordance with the principles of the present inventionwith a connector plug of ane electrode lead inserted therein.

FIG. 6 is a side sectional view of a further embodiment of a connectivepart constructed in accordance with the principles of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a conventional pacer housing 1 having a molded,transparent connective part 2. The connective part 2 includes a femalesocket 3. The inner end of the socket 3 is provided with a longitudinalbore 7 having a relatively small diameter. The bore 7 is provided with acontact surface 4 adjacent to which threads for a set or lock screw 5are located in a bore 6 oriented orthogonally relative to the femalesocket. The housing 2 is hermetically sealed in relation to the moldedpart 2 and the contact between the interior electronics and the contactsurface 4 is achieved by means of a feed-through. The feed-through is aceramic plug, typically made of alumina, into which one or more leadshave been soldered. This lead is bonded (e.g. ultrasonically welded) tothe electronics and to the contact surface 4. The ceramic plug issoldered or brazed with gold into a sleeve made of titanium. Thisoperation may be done at any time before the assembly of the pacerhousing 2. The sleeve is welded into an opening in the housing 2 in asealing manner during the assembly of the pacer housing 2 that normallyis formed by two halves. Before the connective part is molded onto thehousing, these halves are welded together and sealed.

FIG. 2 illustrates a lead 15 having a proximal connecting plug 10 and adistal, transvenous, intracardial electrode 16 as well as an attachmentelement 17 for suturing the proximal end of the lead in the body of thepatient. The connecting plug 10 is designed to be received in the socket3 and the end thereof is provided with a longitudinally projectingcontact pin 11 as well as a cylindrical body provided with sealing rings12, 13, 14 intended to engage and seal against the corresponding innercylindrical surface of the female socket 3. The shape of the pin 11corresponds to the shape of the bore 7. When the plug 10 is insertedinto the socket 3 the pin 11 engages the contact surface 4 and theset-screw in the bore 6 can be tightened against the pin 11 in order tosecurely lock the plug 10 in the socket 3. The complexities involved inholding the bores, contact surfaces and threads in position and keepingthem open and tree from the molding material during the molding processare evident.

For simplicity, the above prior art device has been illustrated as beingunipolar. A bipolar embodiment naturally will be more complex tomanufacture. The preferred embodiments of the invention described belowwill relate to bipolar embodiments.

FIGS. 3-5 show a preferred embodiment of the invention having a tubularmember 20. For clarity, all reference signs have not been repeatedthroughout all drawings.

The member has a tube 21 with two open ends 22, 23. One end 22 is to bewelded into an opening in the pacer housing. The tube 21 is made of thesame metal as the pacer housing, in this case titanium. The opposite end23 of the tube 21 is provided with a ceramic plug 26 fitting snugly inthe tube 21 and soldered with for instance gold against the inside ofthe tube 21. A metallic tubular sleeve 27 serving as a contact sleevehas been molded or bonded into the ceramic plug 26.

The ceramic plug 26 is provided with an interior bore corresponding tothe shape of the proximal part of the male connector in the same way asthe molded prior art female connector described above and thus includesan interior sealing surface 53 for engagement with the sealing rings onthe male connector.

The outer side of the outer end of the contact sleeve 27 is free fromceramic and extends out past the end of the tube 21, thus forming acontact surface for connection to the interior of the housing.

The inner bore of the ceramic plug is closed by a metal plug 20 28having an inner bore at the inner end sized to correspond to the contactpin of the male connector and forming the innermost part of the innerbore of the ceramic plug. The inner bore of the metal plug 28 alsocomprises an inner, circumferential groove 30. The outer end of themetal 28 plug extends out from the ceramic, past the end of the contactsleeve 27, thus forming a second contact surface. The metal plug 28 maybe molded into the ceramic plug 26 or may be a separate part insertedand bonded into the inner bore of the ceramic plug.

The end part 31 of the inside of the contact sleeve 27 is not coveredwith the ceramic material. In this way an inner circumferential grooveis obtained in the inner bore of the ceramic plug 26. The bottom of thegroove consists of the metal in the contact sleeve 27.

Thus, when the ceramic plug 26 has been soldered or bonded into place,the second end 23 will be completely sealed by the plug 26 althoughallowing electrical connection to the interior of the tube via thecontact ring 27 and the metal plug 22. It should be noted that severalconcentric contact rings in a staggered configuration separated byinsulating ceramic material could be used. The number of the connectionsthus would be limited only by the constraints given by the dimensions.

The manufacturing steps involved in the above can be carried out inadvance as desired so as to achieve a prefabricated tube.

The end of the prefabricated tube can be welded to the pacer housing andthe housing parts can be welded together after the connection ofinterior leads from the interior electronics to the contact ring and theplug, should this be desired. The remaining parts, i.e. the meansachieving the contact between the contact rings and the contact surfaceson the male connector part on the lead and the means locking or fixatingthe male connector part in the socket, can easily be insertedafterwards. This means for instance that these parts would not interferewith the standard helium-based procedures for testing the housing withconnector for leaks or that these parts would not be affected by theleak testing procedure.

FIG. 3 shows the main components of the tubular member, the tube 21 withthe ceramic plug 26, a locking arrangement 40 and two circular springcontacts 50, 51. The spring contacts are similar to the spring contactsused in U.S. Pat. No. 4,934,366.

The locking arrangement 40 is designed in a similar way as the leadlocking device disclosed in U.S. Pat. No. 4,262,982, herewithincorporated by reference.

The tube 21 preferably is of the same material as the pacer housing,which normally is made of titanium. The ceramic plug may for instance bemade of alumina A1_(O) ₃, and the contact rings may for instance be madeof stainless steel or of titanium.

FIG. 4 shows the tubular connective member in an assembled state andFIG. 5 shows the tubular connective member mounted in a pacer housing60. The male connector plug 110 is shown inserted into the connectivemember.

The lead locking arrangement 40 has a resilient ring 70 mounted in aninterior, circumferential groove 71 in an inner sealing surface 54 in ahollow locking cylinder 41 fitting in the open end of the tube 21. Theresilient ring is mounted so as to be located directly behind thehindmost sealing ring 116 on the plug 110. The resilient ring has aninner circumferential locking flange 72 biased inwardly into the centralbore. When the plug 110 is inserted into the connective member, thesealing rings 112, 113, 114 and 116 thus will pass the flange and thehindmost sealing ring 116 will be held by the flange 72 against amovement outwardly from the connective member 40. Other lead lockingmeans that could be used in this embodiment are for instance disclosedin U.S. Pat. No. 4,934,366, the teachings of which are incorporatedherein by reference.

FIG. 5 shows how the tube has been mounted in a pacer housing 60 andwelded to an opening 61 in the housing via flanges located on theoutside of the tube ends. FIG. 5 also shows a male connector plug 110inserted in the tubular member. The plug has a contact pin 111, acontact surface 118 and four sealing rings 112, 113, 114, 116. Thesealing rings 112-114, 116 are in engagement with the interior sealingsurfaces 53, 54 and the spring contacts are in contact pin 111respectively with the contact surface 118.

The connector means can be achieved in a simple way compared with theprior art molded connector means.

As mentioned above, the ceramic part can be soldered into the tube inadvance by similar methods as used when obtaining the feed-through inthe prior art. The tube then is placed in the opening in one of thepacer housing halves and may supported by a support 62 located in thehousing, should this prove desirable. The support in this case is abracket being a part of the inner module in the pacer housing having anopening that is complementary to the outside of the tube. Conductors 55,56 are bonded (typically by means of ultrasonic welding) to theconnecting parts of the an electronic circuit board 57 and to the partsof the contact ring and the metal plug that are accessible at the end ofthe tube. The housing halves then are assembled and the two halves andthe ends of the tube are welded together by means of a laser beam toform a sealed unit. This unit then is tested for leakage, for instanceby means of standard helium-based procedures. It should be noted that noother kinds of work operations than those already used in the prior artare necessary.

The pacer then is finished by slipping the resilient spring contactsinto the respective interior grooves in the ceramic plug and byinserting and bonding the lead locking means into place in the open endof the tube.

The new connective part thus is very simple to manufacture and to mountin the pacer housing. The welding and sealing of the housing onlyincludes the additional step of welding the ends of the tube to theedges of the openings in the housing, which is performed in the sameoperation as the welding of the two housing halves. After the weldingoperation, no further operations are necessary, except for the simpleinsertion of spring contact rings and lead-locking mechanism.

Since the tube after the welding operation in principle forms anintegral part of the pacer housing, a high degree of tightness andintegrity is obtained. The tube will ensure a high strength and a highdurability of the connective part, whilst the ceramic plug will ensure ahigh degree of tightness in view of the large contact area betweenceramic plug and tube that can used for soldering, i.e. sealing.

One important feature of the invention is the ability to achieve a highcapacitance between contact ring and tube. The ring and tube will beseparated by the ceramic, which is chosen to be insulating and thus is adielectricum.

The preferred embodiment naturally has a high capacitance since thecontact ring has to extend a long way along the tube. This capacitanceof course can be increased if a capacitor is connected in-between theouter tube and the contact ring.

In an alternative embodiment, illustrated in FIG. 6, a tube 121 hasopposite ends 122, 123 and the mid-section of the tube 121 is providedwith two relatively small lateral openings 124, 125. The openings 124,125 are sealed by means of a ceramic plug 126 fitting snugly in the tubeand soldered with gold or otherwise bonded against the inside of thetube. Two contact rings 127, 128 have been molded into the ceramic plug.

The ceramic plug 126 is provided with an interior bore corresponding tothe shape of the proximal part of the male connector in the same way asthe molded prior art female connector described above. The ceramic plugthus includes an interior-sealing surface 153 for engagement withsealing rings on the male connector.

The central part of the inside of each of the contact rings is notcovered with the ceramic material. In this way two inner circumferentialgrooves 130, 131 are obtained in the inner bore of the ceramic plug. Thebottom of the grooves consists of the metal in the contact rings. Twoopenings 132, 133 are also provided in the outer surface of the ceramicplug 126 that may be made to coincide with the lateral openings 124, 125in the tube wall. These openings allow access to the contact rings 127,128 when the ceramic plug 126 has been mounted correctly in the tube121. Leads for contacting the interior of the housing can be bonded tothe parts of the contact rings 127, 128 accessible through the openings124, 125 and 132, 133.

Typical dimensions for a tube intended to house a standard IS-1 maleconnector are for instance an inner diameter of 5 mm, a wall thicknessof 0.3 mm (i.e. the same as the thickness of typical pacer housingwalls) and a diameter of the holes 124, 125 of about 2 mm. A minimumarea of about 4 mm² is necessary for the equipment presently used forbonding leads to metallic surfaces. The length of the tube is of courseadapted to the specific housing into which it is to be placed, but mighttypically be about 25 mm.

Thus, when the ceramic plug 126 has been soldered or bonded into place,the openings 124, 125 will be completely sealed by the plug 126 althoughallowing electrical connection between the interior of the tube and theinterior of the housing via the contact rings 127,128.

The inner end 123 of the tube 121 is closed by means of a ceramic plug170 soldered into the tube. The plug 170 may be made in one piece withthe plug 126 or, as illustrated, in a separate piece.

The grooves 130, 131 contain spring contact rings 150, 151 of the sametype as the ones described in the preferred embodiment described above.

The locking arrangement 140 is located in the same place and areidentical to the locking arrangement described in the above preferredembodiment. The locking arrangement therefore is not described in moredetail here.

It should be noted that the size of the openings 124, 125 beingnecessary to allow the bonding of the leads to the parts of the contactrings accessible through the openings 124, 125 and 131, 132 is small, inrelation to the entire circumference and to the length of the tube. Theopenings thus do not affect the structural integrity of the tube. Thecontact rings 127, 128 moreover overlap the openings and are bondedthereto by means of the intermediate layer of ceramics, in this waystrengthening the area in which the openings are located.

Typical dimensions for a tube intended to house a standard IS-1 maleconnector are for instance an inner diameter of 5 mm, a wall thicknessof 0.3 mm (i.e. the same as the thickness of typical pacer housingwalls) and a diameter of the holes 124, 125 of about 2 mm. A minimumarea of about 4 mm² is necessary for the equipment presently used forbonding leads to metallic surfaces. The length of the tube is of courseadapted to the specific housing into which it is to be placed, but mighttypically be about 25 mm.

These dimensions of course can be varied as long as the tube remainsstructurally intact, i.e. as long as the tube has a strength andrigidity that is sufficient to prevent loads, including thermalstresses, on the housing and/or the connector to be transferred astensile forces to the ceramic parts. Of course, low tensile forces notexceeding the tensile strength of the ceramic could be accepted. Sincethere are standards regarding the loads a pacer housing and connectorshould be able to withstand and regarding the overall tightness of thehousing, variations of the dimensions only would involve standard stresscalculations and dimensioning well within the scope of the man in theart. It should be noted that this also could take the degree ofsoldering between ceramic plug and tube into account, since this woulddetermine the extent to which tube and ceramic would function as acomposite without going outside the ordinary skill of the man skilled inthe art.

The number of lateral openings of course only is limited by the lengthof the tube and by the above considerations regarding the structuralintegrity.

It should also be noted that the main design features of the above twoembodiments could be combined in different ways. One or several of theconnections of the above first embodiment thus could be combined withone or several connections according to the above second embodiment. Forinstance, should it be desired to provide four contact means for a leadwith four conductors, two of them could for instance be connected via anend plug designed in accordance with the first embodiment and the othertwo by means of lateral openings designed in accordance with the secondembodiment.

It should also be noted that the ceramic material in the connectorpartly or entirely could be replaced by another insulating material, forinstance a suitable plastics material.

Although modifications and changes may be suggested by those skilled inthe art, it is the intention of the inventors to embody within thepatent warranted hereon all changes and modifications as reasonably andproperly come within the scope of their contribution to the art.

We claim:
 1. A pacer housing comprising: a metallic housing enclosure; aconnector arrangement adapted to receive a contact plug of an electrodelead, said connector arrangement comprising a tubular member disposedinside said housing and having a first end and a second end oppositesaid first end, said first end of said tubular member being attached, byan attachment selected from the group consisting of a weld and bond, toan opening in a wall of said housing, and said second end of saidtubular member being closed; said tubular member being formed by a tubecomprised of a metal attachable to said housing enclosure by saidattachment, said tube having a length and being continuous along anentirety of said length; a plurality of interior elements adapted formechanical and electrical contact with said contact plug; and aninsulating plug in comprised of ceramic material fitted into an interiorof said tube and closing said second end of said tubular member andhaving said interior elements mounted therein, said insulating plugbeing coaxial with said tube and holding said interior elements atrespective positions for producing said mechanical and electricalcontact with said contact plug, said insulating plug being attached tosaid tube by an attachment technique selected from the group consistingof soldering and bonding.
 2. A pacer housing as claimed in claim 1wherein said housing enclosure has a housing interior, and furthercomprising a metallic tubular sleeve embedded in said ceramic plug andhaving an end projecting from said ceramic plug exposing an exteriorcontact surface for providing electrical contact with said housinginterior, and said sleeve having an opposite end which is exposed in aninterior of said tubular member to produce an inner contact surfaceadapted for electrical and mechanical contact with said contact plug. 3.A pacer housing as claimed in claim 1 wherein said housing enclosure hasan interior, and further comprising a metallic plug embedded in saidceramic plug, said metallic plug having an outer end projecting fromsaid ceramic plug to provide an exterior contact surface for electricalcontact with said interior of said housing.
 4. A pacer housing asclaimed in claim 3 wherein said metallic plug has an inner end oppositeto said outer end with a bore therein in communication with an interiorof said ceramic plug, and adapted to receive and electrically contactsaid contact plug.
 5. A pacer housing as claimed in claim 1 wherein saidhousing enclosure has an interior, and wherein said ceramic plug has acontact ring therein having an interior surface adapted for makingelectrical contact with said contact plug, and a contact surface, andwherein said metal tube has a lateral opening therein exposing saidcontact surface for establishing electrical contact to said interior ofsaid housing.
 6. A pacer housing as claimed in claim 5 wherein saidcontact ring comprises a metal ring attached to said ceramic plug by anattachment technique selected from molding and bonding, and wherein saidceramic plug has an exterior with an opening therein in registrationwith said lateral opening in said metal tube allowing access to saidring from an exterior of said tube.
 7. A pacer housing as claimed inclaim 6 wherein said metal ring has an interior that is free of saidceramic forming a peripheral groove in an interior of said ring allowingaccess to said ring from said interior of said metal tube.